Well we could have skipped the heated sensor issue with having known the
year, but as it frequently occurs on these groups, no year mentioned,
anyway, the o2 sensor generates it own voltages as the sensor heats up and
reacts to the amount of 02 in the exh. stream. Open loop is rich, the .5
volts is default for the pcm to operate from,till the sensor heats up and
coolant temps come up.
"Scott Buchanan" <t120rv@[EMAIL PROTECTED]
> wrote in message
news:veqdnWFTOr1VUpPVnZ2dnUVZ_gqdnZ2d@[EMAIL PROTECTED]
>
> 1995 Grand AM. It is not a heated sensor.
> I think that the coolant temp was not more than 80 deg. F since it had
> been
> running less than a minute before going into closed loop. I'll check
> tomorrow. As mentioned, the O2 voltage had not reached .5 volt so it
> should
> not have been hot enough to work yet. This is assuming that open loop is
> running rich and not lean not allowing it to reach .5 volts.
>
> What should the coolant temperature be?
>
>
> "Shep" <djsljsrn@[EMAIL PROTECTED]
> wrote in message
> news:1208894913_425@[EMAIL PROTECTED]
>> Coolant temp and the temp of the O2 sensor, late model obd11 engines
have
> a
>> heated sensor, no mention your year though.
>> "Scott Buchanan" <t120rv@[EMAIL PROTECTED]
> wrote in message
>> news:BeCdnZh4R99r9JDVnZ2dnUVZ_gydnZ2d@[EMAIL PROTECTED]
>> > My car generally runs good. A problem is that sometimes, about a
minute
>> > after a cold start, it will stumble for a few seconds. Usually I'll
be
> in
>> > a
>> > parking lot or in the driveway so it is not much of an issue. Last
week
> it
>> > happened after I pulled into traffic.
>> >
>> > A scan tool shows that it goes into closed loop about a minute after
a
>> > cold
>> > start (40 deg F.). It cycles back to open loop then closed several
>> > times
>> > before it stays closed. This happened before the O2 sensor reached .5
>> > volts.
>> > I think that this might be a clue to the problem. Once running hot,
the
> O2
>> > sensor will cycle from rich to lean several times a second.
>> >
>> > My question is what allows the engine to go into closed loop?
>> >
>> > Thanks
>> >
>> >
>>
>>
>>
>>
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